Analysis of left ventricular function from gated first-pass and multiple gated equilibrium acquisitions

Measurement of ventricular function with radionuclide techniques

The noninvasive assessment of resting left ventricular performance has become an integral part of the evaluation of patients with known or suspected cardiac disease, having important diagnostic, therapeutic, and prognostic significance. This article details the wide range of clinical diagnostic possibilities available by dynamic imaging of myocardial function using scintigraphic techniques, including gated planar and tomographic blood pool imaging, first-pass radionuclide angiography, and gated tomographic perfusion imaging. The clinical and technical aspects described should be useful to the cardiologist intent upon supervising the performance of these tests, as well as providing their interpretation.

Transit time heterogeneity of bolus flow through the heart and lungs in patients with left-to-right intracardiac shunt

Knowledge of the contributions of transit time heterogeneity to the cardiopulmonary system is important for understanding cardiopulmonary function in patients with intracardiac shunt. We determined the heterogeneity of blood transit times occurring between the right atrium and the left ventricle. Eighty two patients with suspected left-to right shunt were investigated with first-pass 99mTc-labelled red blood cell radiocardiography at supine rest. Forty two of them had a pulmonary-to-systemic flow ratio (Qp:Qs) of less than 1.2 and they served as a control group. The remaining study subjects had a Qp:Qs ratio of 1.7 +/- 0.3 (mean +/- SD). The patients with shunt had significantly greater (p < 0.001) heterogeneity of transit times (49 +/- 9%) than in the controls (39 +/- 7%). Overall heterogeneity of cardiopulmonary transit times in patients with shunt showed a curvature relationship; the highest values were centred in patients with moderate to severe shunt (1.5 < Qp:Qs < 2.5). The results suggest that the increased heterogeneity of transit times mainly occurs within the pulmonary capillary bed in patients with intracardiac shunt. This is probably due to the recruitment of the open capillaries without vessel distension.